Mechanical roasting or desulfurizing furnace.



N0. 804,227. PATENTED NOV. 14, 1905.

H. HOWARD. MECHANICAL ROASTING 0R DESULFURIZING FURNACE.

APPLICATION FILED APR.11. 19.05.

2 SHEETS-SHEET l.

UNITED STATES PATENT OFFICE.

HENRY HOWARD, OF BROOKLINE, MASSACHUSETTS, ASSIGNOR TO MERRIMAO CHEMICALCOMPANY, OF NORTH VVOBURN, MASSA- OHUSETTS, A CORPORATION OFMASSACHUSETTS MECHANICAL ROASTING OR DESULFURIZPNGFURNACE- Patented Nov.1%, 1905.

Application filed April 11, 1905. Serial No. 255,065.

To all whom it may concern:

Be it known that I, HENRY HOWARD, a citizen of the United States, and aresident of Brookline, county of Norfolk, State of Massachusetts, haveinvented an Improvement in Mechanical Roasting or DesulfurizingFurnaces, of which the following description, in connection with theaccompanying drawings, is a specification, like figures on the drawingsrepresenting like parts. 1

This invention relates to roasting or desulfurizing furnaces of the typewherein the ore or other material to be treated is shpported within thefurnace on shelves oors arranged one above the other, the material beingfed into the furnace at the tdp and being agitated or turned over on thedifferent shelves by suitable stirrers and passing *downward from shelfto shelf through the furnace.

In the well-known Herreshoff roasting-furnace, one form of which isshown in United States Patent No. 616,926, dated January 3, 1899, thefurnace is provided with an upright rotatable hollow shaft havingradially extended stirrer-arms which carry teeth or plows which stir upand turn over the material on the different shelves. The rotatable shaftis made hollow to permit the passage therethrough of an air-current tokeep down as much as possible the temperature of the connections betweenthe shaft and the stirrerarms, the hot air escaping from the upper endof the shaft. In such furnace the material is fed onto the topmostshelf, and it is gradually burned as it passes downward from shelf toshelf in well-known manner. Such furnaces are very successful intreating dry ore or other material, such as American pyrites, which canbe stirred up during the roasting process without sticking orconglomerating in large masses. When treating material containingconsiderable moisture-such, for instance,as what are technically termedwashed Spanish fines these furnaces are not efficient unless thematerial is drled prior to its introduction to the furnace, therebyinvolving additional labor and expense and a large expenditure of time.If such material is introduced to the furnace without such prior drying,it blocks the feed and cakes and balls up in such large masses that thestirrers cannot break it up, and the stirrers themselves are oftenbroken.

In my present invention I have utilihed a large proportion of the wasteheat of the furnace to dry the incoming material, the arrangement beingsuch that the material is dried and stirred on the top or arch of thefurnace and is fed therefrom to the interior of the furnace to beroasted. I have also provided a large storage for ore, which isavailable in keeping the feed ech nism supplied with ore for twelve houil or': more without replenishing the ore s storedaamounting in practiceto sev ral tons. I have also provided means to catch or trap allargeproportion of the dust which escapes w th the burner gas or fumes,therebyhnsuring a very pure gaseous product from the furnace. I havealso made an improvement in the feed mechanism whereby the same is veryaccessible and can be readily repaired or replaced in case of accident.

The various novel features of my invention will be fully described inthe subjoined specification and particularly pointed out in thefollowing claims.

Figure 1 is a top plan view of a sufficient portion of a desulfurizingplant to be understood with one embodiment of my invention appliedthereto, the top or cover of the central furnace being removed to showthe parts beneath. Fig. 2 is a partial vertical section on the line 2 2,Fig. 1, taken through the vertical center of the furnace, the latterbeing broken out between its top and bottom to economize space, thelower portion being shown in elevation. Fig. 3 is an enlarged detailtaken on the line 3 3, Fig. 2, of one of the stirrers shown in the upperpart of Fig. 2. Fig. 4; is a plan view and part section, enlarged, ofthe connection between the rotating tubular shaft of the furnace and theauxiliary or feed stirrer-arms, taken on the line 44, Fig. 5; and Fig. 5is a side elevation and part section of such connection on the line 5 5,Fig. 4:.

In the drawings, having more particular reference to Fig. 2, the uprightcircular furnace 1, having a top arch 2 and a plurality of shelves3arranged one above the other (one of such shelves being shown) toreceive the material to be treated, said material being agitated andpassed from shelf to shelf by stirrers 4:, depending from radialrevolving stirrer-arms 5, the upright tubular air-shaft 6, extendedupward through the center of the furnace and to which the stirrer-armsare attached, and the gearing 7 8, connecting the lower end of the shaft6 with a power-driven shaft 9 to rotate said tubular shaft, and therebyactuate the stirring devices, may be and are all substantially as usualin furnaces of the type hereinbefore referred to and illustrated in theHerreshoif patent. A depending annular flange 10, secured'to the shaft6, enters an annular concentric gutter 11, secured to the top arch 2,forming a species of sealing device to prevent the escape of the hotgases liberated by the roasting action in the furnace in substantiallyusual manner.

In accordance with my present invention I erect upon the furnace adrying-chamber 12, conveniently made of sheet metal and preferablyhaving a cover 13, a runway 14, carried on the covers of the severalfurnaces extending the length of the group, the runway being partlyshown in Fig. 1. A hopper 15, Fig. 1, opens into the chamber adjacentthe runway, the material to be treated being brought up in suitablebarrows or cars on the runway and dumped into the hoppers, passingthence into the drying-chambers, the bottom of each chamber being formedby the top arch 2 of its furnace. The upper end of the rotatable shaft 6passes up through the chamber to a point near its cover 13, (see Fig.2,) and a split collar 16 (see Figs. 4 and 5) is clamped rigidly uponthe shaft by bolts 17, the collar having an annular upturned flange 18surrounding its upper end. Into the groove formed by the collar and theflange is inserted the lower end of a stack 19, suitably bolted to thecover of the chamber and extending a suitable height above it, a damper20 being arranged in' the stack for a purpose to be described. Each halfof the collar has a radiall y-extended seat 21, in which is bolted astirrer-arm 22, and to each of the arms is securely bolted a series ofdepending stirrers or plows 23, one of which is shown separately in Fig.3. The stirrers are curved in the direction of their length and madeslightly scoop like to better break up and turn over the material in thechamber, the stirrers on one arm being so spaced as to track between thepaths of the stirrers on the other arm, and'the two sets of stirrers arefaced to act in the same direction.

As the material is dumped into the chamher the rotation of the shaft 6causes the stirrers to agitate and distribute the material, at firstforming a bed upon the highly-heated arch, so *that this bed of ore orother material quicklybecomes dry and hot, so that the incoming materialcontacts therewith, and as it is spread and distributed by the stirrersit in turn becomes dry and hot.

A feed duct or tube 24 is led into the drying-chamber from its side wallradially toward the tubular shaft, the inner end of the duct beingvdownturned at 25, Fig. 2, into the upper portion of the furnace throughan opening in the top arch made for the purpose and fitting tightly intosuch opening.

The feedduct lies just below the paths of the lower ends of thestirrers, and it is provided with an inlet 26 in its top near the wallof the chamber, the hopper 15 and inlet 26 being located far apart, asshown in Fig. 2. 7

As the dried hot material is spread out in the chamber it is graduallyworked over to the inlet and passes therethrough into the duct, in whichit is positively pushed forward and forced into the furnace by afeed-screw 27 of well-known construction.

The material is so thoroughly heated and dried in the drying-chamberthat it cannot cake or collect in large lumps and it is readily fed indry and broken-up condition into the furnace onto the topmost one of theshelves 3 to begin burning. A great deal of the waste heat at the toparch of the furnace is thus utilized by the drying-chamber; but in orderto still further increase the heating efiect I provide means tointroduceto the chamber more or less of the very hot air rising through the shaft6. To this end the inlet 28 of a suitable blast fan or blower in thecasing 29 is connected with the stack 19 below the damper 20, and theoutlet 30 of the blower is intro duced into the chamber through its sidewall above the material therein, so that by closingthe damper a hotblast of air will be directed through the chamber across the incomingmaterial.

By properly manipulating the damper the amount of hot air can beregulated as desired, this hot air passing up through the shaft 6 beingutilized to perform useful work instead of permitting it to go to waste,as is now customary.

By the construction described I am able to feed finely-divided ore orpyrites and washed Spanish fines containing a large percentage ofmoisture directly to the furnace without any previous drying operation,thereby not only greatly facilitating the treatment of such material,but also greatly reducing the cost of treatment thereof.

A driving-shaft 31 is extended along the row of furnaces and is providedwith pulleys 32, which are connected by belts or chains 33 with theseveral blowers to actuate the same,

and the same shaft is utilized to operate the feed-screws 27. For thispurpose each screwshaft 34 is extended a considerable distance beyondthe outer end of the feed-duct and supported in bearings 35, and aworm-gear 36 on the shaft is caused to mesh with a worm 37 on a shorttransverse shaft 38, (see Fig. 1,) supported in bearings on struts 39.ley 40 on each shaft 38 is belted to a pulley 41 on the commonactuating-shaft 31, by which means the several feed-screws arepositively A puldriven, and I prefer to use expansion-pulleys of anysuitable construction, so that the speed of the feed-screws may beconveniently ad justed and varied as desired.

The means for driving the feed-screws is so arranged that in case ofbreakage of any of the parts repairs can be rapidly executed, obviatingcooling down of the furnace and consequent loss of production.

The. hot burner-gas is discharged through an opening 42, Fig. 2, in theside wall of the furnace near the top arch, and a great deal of dust andother impurities are apt to pass out with the gas. To arrest such dust,and thereby greatly increase the purity of the gas, I have provided adust-arrester (shown as an elongated box 43) extended radially from thefurnace and with the inner end of which box the opening 42 registers.

The main outlet-flue 4:4: for the gases from the several furnaces of thebattery is connected with each box 43 by a pipe 45, which leads from thetop of the box in an upright direction and then bends and passes inahorizontal direction to the flue 44..

As the hot gases rush out of the furnace into the box the heavierparticles of dust impinge against the outer end of the box and fall tothe bottom, while the lighter gas thus freed from the dust passes upwardout of the top of the box into the pipe 45 to the outlet-flue in a muchpurified condition. A cover or door 46 at the outer end of the boxenables the solid contents thereof to be cleaned out from time to timewithout materially disturb ing the operation of the furnace.

The drying-chamber forms a storage-recep tacle for a large quantity ofore, (in actual practice two tons or more,) so that suflicient drymaterial is provided for the feed mechanism without replenishing thechamber for ten or twelve hours.

The cover of the chamber isleft open above the feed mechanism, as at 13so that the action of the stirrers may be observed from time to time,and also permitting the escape of the hot air from'the chamber.

So far as I am aware it is broadly new to utilize a large proportion ofthe waste heat.

of furnaces of this type to effect a preliminary heating and drying ofthe material before it is introduced into the interior of the furnace,and accordingly my invention is not restricted to the preciseconstruction and arrangement herein shown and described, as variouschanges and modifications may be made by those skilled in the artwithout departing from the spirit and scope of my invention.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is-

1. In afurnace of the class described, adrying-chamber mounted thereonto receive and dry the material to be treated, manually-controlled meansto directly introduce waste heat from the furnace into thedrying-chamber and subject the contents thereof to the action of suchheat, an agitating device within the chamber, and means to positivelyfeed the dried material from the chamber into the interior of thefurnace.

2. In afurnace of the class described, an upright, rotatable, tubularair-shaft extended through the top arch, a partially-closed.drying-chamber on the arch to receive the material to be treated, meansto introduce hot air from the shaft to said chamber, to dry the contentsthereof, means to agitate and distribute the material introduced intothe chamber, and a device to positively feed the dried material to theinterior of the furnace.

3. In a furnace of the class described, a rotatable, tubular air shafthaving attached stirrer-arms, a partially-closed drying-chamber on thetop arch of the furnace, to receive and dry the material to be treated,means to introduce hot air from said shaft into the chamber, a feed-ductadjacent the bottom of the chamber and opening into the interior of thefurnace, and a device to positively force the dried material through thesaid duct into the furnace.

4. In a furnace of the class described, a central tubular air-shafthaving attached stirrerarms, a partially-closed drying-chambersuperposedupon the top arch of the furnace, to receive the material to be treated,stirrers carried by the shaft to agitate and spread the incomingmaterial in said chamber, a feed-duct within the latter below the pathsof the stirrers and opening into the furnace, a feed-screw in the ductto positively force the dried material from the chamber into thefurnace, a deep bed of hot material being maintained upon the top arch,and means to introduce into the drying-chamber the hot air from thetubular shaft. I

5. In a furnace of'the class described, a drying-chamber upon the toparch thereof, to receive the material to be treated, a tubular,rotatable shaft extended up through the furnace and said chamber,stirring means within the chamber and carried by the shaft, means toconvey the hot air from the upper end of the shaft into the chamber, todry the contents thereof, the chamber having an outlet for the heatedair, and positively acting feeding means within the chamber to force thedried material therefrom into the furnace.

6. In a mechanical roasting-furnace of the class described, a closeddrying-chamber superposed upon the top arch thereof, to receive thematerial to be treated, an upright, central, tubular rotatable shaftextended through the furnace and chamber, a stationary stackcommunicating with the upper end of the shaft, means to conduct the hotair'from the stack and force it into the chamber through its side wall,a coupling on the shaft within the chamber, radial arms attached theretoand carrying depending stirrers to agitate and distribute the incoming'material, a feed-duct in the chamber below the paths of movement ofthrough the top arch, a positively-driven feedscreW in the duct to forcethe dried material through the duct into the furnace, and means withinthe chamber to stir the material and conduct it to the entrance of thefeed-duct.

In testimony WlIIBI'G'Of Ihave signed my name to this specification inthe presence of two subscribing witnesses.

HENRY HOWARD.

Witnesses:

JOHN C. EDWARDS, ELIZABETH R. MORRISON.

